tools/cargo_embargo/src/main.rs

// Copyright (C) 2022 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

//! Converts a cargo project to Soong.
//!
//! Forked from development/scripts/cargo2android.py. Missing many of its features. Adds various
//! features to make it easier to work with projects containing many crates.
//!
//! At a high level, this is done by
//!
//!     1. Running `cargo build -v` and saving the output to a "cargo.out" file.
//!     2. Parsing the "cargo.out" file to find invocations of compilers, e.g. `rustc` and `cc`.
//!     3. For each compiler invocation, generating a equivalent Soong module, e.g. a "rust_library".
//!
//! The last step often involves messy, project specific business logic, so many options are
//! available to tweak it via a config file.

mod bp;
mod cargo;
mod config;

use crate::config::legacy;
use crate::config::Config;
use crate::config::PackageConfig;
use anyhow::bail;
use anyhow::Context;
use anyhow::Result;
use bp::*;
use cargo::{
    cargo_out::parse_cargo_out, metadata::parse_cargo_metadata_file, Crate, CrateType, ExternType,
};
use clap::Parser;
use clap::Subcommand;
use log::debug;
use once_cell::sync::Lazy;
use std::collections::BTreeMap;
use std::collections::VecDeque;
use std::fs::File;
use std::io::Write;
use std::path::Path;
use std::path::PathBuf;
use std::process::Command;

// Major TODOs
//  * handle errors, esp. in cargo.out parsing. they should fail the program with an error code
//  * handle warnings. put them in comments in the android.bp, some kind of report section

/// Rust modules which shouldn't use the default generated names, to avoid conflicts or confusion.
static RENAME_MAP: Lazy<BTreeMap<&str, &str>> = Lazy::new(|| {
    [
        ("libash", "libash_rust"),
        ("libatomic", "libatomic_rust"),
        ("libbacktrace", "libbacktrace_rust"),
        ("libbase", "libbase_rust"),
        ("libbase64", "libbase64_rust"),
        ("libfuse", "libfuse_rust"),
        ("libgcc", "libgcc_rust"),
        ("liblog", "liblog_rust"),
        ("libminijail", "libminijail_rust"),
        ("libsync", "libsync_rust"),
        ("libx86_64", "libx86_64_rust"),
        ("libxml", "libxml_rust"),
        ("protoc_gen_rust", "protoc-gen-rust"),
    ]
    .into_iter()
    .collect()
});

fn renamed_module(name: &str) -> &str {
    if let Some(renamed) = RENAME_MAP.get(name) {
        renamed
    } else {
        name
    }
}

/// Command-line parameters for `cargo_embargo`.
#[derive(Parser, Debug)]
struct Args {
    /// Use the cargo binary in the `cargo_bin` directory. Defaults to cargo in $PATH.
    ///
    /// TODO: Should default to android prebuilts.
    #[clap(long)]
    cargo_bin: Option<PathBuf>,
    /// Config file.
    #[clap(long)]
    cfg: PathBuf,
    /// Skip the `cargo build` commands and reuse the "cargo.out" file from a previous run if
    /// available.
    #[clap(long)]
    reuse_cargo_out: bool,
    #[command(subcommand)]
    mode: Option<Mode>,
}

#[derive(Clone, Debug, Subcommand)]
enum Mode {
    /// Converts a legacy `cargo2android.json` config file to the equivalent `cargo_embargo.json`
    /// config.
    Convert {
        package_name: String,
        #[arg(long)]
        no_build: bool,
    },
    /// Dumps information about the crates to the given JSON file.
    DumpCrates { crates: PathBuf },
}

fn main() -> Result<()> {
    env_logger::init();
    let args = Args::parse();

    let json_str = std::fs::read_to_string(&args.cfg)
        .with_context(|| format!("failed to read file: {:?}", args.cfg))?;
    // Add some basic support for comments to JSON.
    let json_str: String = json_str.lines().filter(|l| !l.trim_start().starts_with("//")).collect();

    match &args.mode {
        Some(Mode::Convert { package_name, no_build }) => {
            let legacy_config: legacy::Config =
                serde_json::from_str(&json_str).context("failed to parse legacy config")?;
            let new_config = legacy_config.to_embargo(package_name, !no_build)?;
            let new_config_str = serde_json::to_string_pretty(&new_config)
                .context("failed to serialize new config")?;
            println!("{}", new_config_str);
        }
        Some(Mode::DumpCrates { crates }) => {
            dump_crates(&args, &json_str, crates)?;
        }
        None => {
            run_embargo(&args, &json_str)?;
        }
    }

    Ok(())
}

/// Runs cargo_embargo with the given JSON configuration string, but dumps the crate data to the
/// given `crates.json` file rather than generating an `Android.bp`.
fn dump_crates(args: &Args, json_str: &str, crates_filename: &Path) -> Result<()> {
    let cfg: Config = serde_json::from_str(json_str).context("failed to parse config")?;
    let crates = make_crates(args, &cfg)?;
    serde_json::to_writer(
        File::create(crates_filename)
            .with_context(|| format!("Failed to create {:?}", crates_filename))?,
        &crates,
    )?;
    Ok(())
}

fn make_crates(args: &Args, cfg: &Config) -> Result<Vec<Crate>> {
    if !Path::new("Cargo.toml").try_exists().context("when checking Cargo.toml")? {
        bail!("Cargo.toml missing. Run in a directory with a Cargo.toml file.");
    }

    // Add the custom cargo to PATH.
    // NOTE: If the directory with cargo has more binaries, this could have some unpredictable side
    // effects. That is partly intended though, because we want to use that cargo binary's
    // associated rustc.
    if let Some(cargo_bin) = &args.cargo_bin {
        let path = std::env::var_os("PATH").unwrap();
        let mut paths = std::env::split_paths(&path).collect::<VecDeque<_>>();
        paths.push_front(cargo_bin.to_owned());
        let new_path = std::env::join_paths(paths)?;
        debug!("Set PATH to {:?}", new_path);
        std::env::set_var("PATH", new_path);
    }

    let cargo_out_path = "cargo.out";
    let cargo_metadata_path = "cargo.metadata";
    if !args.reuse_cargo_out || !Path::new(cargo_out_path).exists() {
        generate_cargo_out(cfg, cargo_out_path, cargo_metadata_path)
            .context("generate_cargo_out failed")?;
    }

    if cfg.run_cargo {
        parse_cargo_out(cargo_out_path, cargo_metadata_path).context("parse_cargo_out failed")
    } else {
        parse_cargo_metadata_file(cargo_metadata_path, cfg)
    }
}

/// Runs cargo_embargo with the given JSON configuration string.
fn run_embargo(args: &Args, json_str: &str) -> Result<()> {
    let cfg: Config = serde_json::from_str(json_str).context("failed to parse config")?;
    let crates = make_crates(args, &cfg)?;

    // Find out files.
    // Example: target.tmp/x86_64-unknown-linux-gnu/debug/build/metrics-d2dd799cebf1888d/out/event_details.rs
    let mut package_out_files: BTreeMap<String, Vec<PathBuf>> = BTreeMap::new();
    if cfg.package.iter().any(|(_, v)| v.copy_out) {
        for entry in glob::glob("target.tmp/**/build/*/out/*")? {
            match entry {
                Ok(path) => {
                    let package_name = || -> Option<_> {
                        let dir_name = path.parent()?.parent()?.file_name()?.to_str()?;
                        Some(dir_name.rsplit_once('-')?.0)
                    }()
                    .unwrap_or_else(|| panic!("failed to parse out file path: {:?}", path));
                    package_out_files
                        .entry(package_name.to_string())
                        .or_default()
                        .push(path.clone());
                }
                Err(e) => eprintln!("failed to check for out files: {}", e),
            }
        }
    }

    write_all_bp(&cfg, crates, &package_out_files)
}

fn group_by_package(crates: Vec<Crate>) -> BTreeMap<PathBuf, Vec<Crate>> {
    let mut module_by_package: BTreeMap<PathBuf, Vec<Crate>> = BTreeMap::new();
    for c in crates {
        module_by_package.entry(c.package_dir.clone()).or_default().push(c);
    }
    module_by_package
}

fn write_all_bp(
    cfg: &Config,
    crates: Vec<Crate>,
    package_out_files: &BTreeMap<String, Vec<PathBuf>>,
) -> Result<()> {
    // Group by package.
    let module_by_package = group_by_package(crates);

    // Write an Android.bp file per package.
    for (package_dir, crates) in module_by_package {
        write_android_bp(
            cfg,
            package_dir,
            &crates,
            package_out_files.get(&crates[0].package_name),
        )?;
    }

    Ok(())
}

fn run_cargo(cargo_out: &mut File, cmd: &mut Command) -> Result<()> {
    use std::os::unix::io::OwnedFd;
    use std::process::Stdio;
    let fd: OwnedFd = cargo_out.try_clone()?.into();
    debug!("Running: {:?}\n", cmd);
    let output = cmd.stdout(Stdio::from(fd.try_clone()?)).stderr(Stdio::from(fd)).output()?;
    if !output.status.success() {
        bail!("cargo command failed with exit status: {:?}", output.status);
    }
    Ok(())
}

/// Run various cargo commands and save the output to `cargo_out_path`.
fn generate_cargo_out(cfg: &Config, cargo_out_path: &str, cargo_metadata_path: &str) -> Result<()> {
    let mut cargo_out_file = std::fs::File::create(cargo_out_path)?;
    let mut cargo_metadata_file = std::fs::File::create(cargo_metadata_path)?;

    let verbose_args = ["-v"];
    let target_dir_args = ["--target-dir", "target.tmp"];

    // cargo clean
    run_cargo(&mut cargo_out_file, Command::new("cargo").arg("clean").args(target_dir_args))?;

    let default_target = "x86_64-unknown-linux-gnu";
    let feature_args = if cfg.features.is_empty() {
        vec![]
    } else {
        vec!["--no-default-features".to_string(), "--features".to_string(), cfg.features.join(",")]
    };

    let workspace_args = if cfg.workspace {
        let mut v = vec!["--workspace".to_string()];
        if !cfg.workspace_excludes.is_empty() {
            for x in cfg.workspace_excludes.iter() {
                v.push("--exclude".to_string());
                v.push(x.clone());
            }
        }
        v
    } else {
        vec![]
    };

    // cargo metadata
    run_cargo(
        &mut cargo_metadata_file,
        Command::new("cargo")
            .arg("metadata")
            .arg("-q") // don't output warnings to stderr
            .arg("--format-version")
            .arg("1")
            .args(&feature_args),
    )?;

    if cfg.run_cargo {
        // cargo build
        run_cargo(
            &mut cargo_out_file,
            Command::new("cargo")
                .args(["build", "--target", default_target])
                .args(verbose_args)
                .args(target_dir_args)
                .args(&workspace_args)
                .args(&feature_args),
        )?;

        if cfg.tests {
            // cargo build --tests
            run_cargo(
                &mut cargo_out_file,
                Command::new("cargo")
                    .args(["build", "--target", default_target, "--tests"])
                    .args(verbose_args)
                    .args(target_dir_args)
                    .args(&workspace_args)
                    .args(&feature_args),
            )?;
            // cargo test -- --list
            run_cargo(
                &mut cargo_out_file,
                Command::new("cargo")
                    .args(["test", "--target", default_target])
                    .args(target_dir_args)
                    .args(&workspace_args)
                    .args(&feature_args)
                    .args(["--", "--list"]),
            )?;
        }
    }

    Ok(())
}

/// Create the Android.bp file for `package_dir`.
fn write_android_bp(
    cfg: &Config,
    package_dir: PathBuf,
    crates: &[Crate],
    out_files: Option<&Vec<PathBuf>>,
) -> Result<()> {
    let bp_path = package_dir.join("Android.bp");

    let package_name = crates[0].package_name.clone();
    let def = PackageConfig::default();
    let package_cfg = cfg.package.get(&package_name).unwrap_or(&def);

    // Keep the old license header.
    let license_section = match std::fs::read_to_string(&bp_path) {
        Ok(s) => s
            .lines()
            .skip_while(|l| l.starts_with("//"))
            .take_while(|l| !l.starts_with("rust_") && !l.starts_with("genrule {"))
            .collect::<Vec<&str>>()
            .join("\n"),
        Err(e) if e.kind() == std::io::ErrorKind::NotFound => "// TODO: Add license.\n".to_string(),
        Err(e) => bail!("error when reading {bp_path:?}: {e}"),
    };

    // If `copy_out` is enabled and there are any generated out files for the package, copy them to
    // the appropriate directory.
    if let (true, Some(out_files)) = (package_cfg.copy_out, out_files) {
        let out_dir = package_dir.join("out");
        if !out_dir.exists() {
            std::fs::create_dir(&out_dir).expect("failed to create out dir");
        }

        for f in out_files.iter() {
            let dest = out_dir.join(f.file_name().unwrap());
            std::fs::copy(f, dest).expect("failed to copy out file");
        }
    }

    if let Some(bp_contents) =
        generate_android_bp(&license_section, cfg, package_cfg, &package_name, crates, out_files)?
    {
        write_format_android_bp(&bp_path, &bp_contents, package_cfg.patch.as_deref())?;
    }

    Ok(())
}

/// Generates and returns a Soong Blueprint for the given set of crates.
fn generate_android_bp(
    license_section: &str,
    cfg: &Config,
    package_cfg: &PackageConfig,
    package_name: &str,
    crates: &[Crate],
    out_files: Option<&Vec<PathBuf>>,
) -> Result<Option<String>> {
    let mut bp_contents = String::new();
    bp_contents += "// This file is generated by cargo_embargo.\n";
    bp_contents += "// Do not modify this file as changes will be overridden on upgrade.\n\n";
    bp_contents += license_section.trim();
    bp_contents += "\n";

    let mut modules = Vec::new();

    let extra_srcs = if let (true, Some(out_files)) = (package_cfg.copy_out, out_files) {
        let outs: Vec<String> = out_files
            .iter()
            .map(|f| f.file_name().unwrap().to_str().unwrap().to_string())
            .collect();

        let mut m = BpModule::new("genrule".to_string());
        let module_name = format!("copy_{}_build_out", package_name);
        m.props.set("name", module_name.clone());
        m.props.set("srcs", vec!["out/*"]);
        m.props.set("cmd", "cp $(in) $(genDir)");
        m.props.set("out", outs);
        modules.push(m);

        vec![":".to_string() + &module_name]
    } else {
        vec![]
    };

    for c in crates {
        modules.extend(crate_to_bp_modules(c, cfg, package_cfg, &extra_srcs).with_context(
            || {
                format!(
                    "failed to generate bp module for crate \"{}\" with package name \"{}\"",
                    c.name, c.package_name
                )
            },
        )?);
    }
    if modules.is_empty() {
        return Ok(None);
    }

    // In some cases there are nearly identical rustc invocations that that get processed into
    // identical BP modules. So far, dedup'ing them is a good enough fix. At some point we might
    // need something more complex, maybe like cargo2android's logic for merging crates.
    modules.sort();
    modules.dedup();

    modules.sort_by_key(|m| m.props.get_string("name").to_string());
    for m in modules {
        m.write(&mut bp_contents)?;
        bp_contents += "\n";
    }
    if let Some(path) = &package_cfg.add_toplevel_block {
        bp_contents +=
            &std::fs::read_to_string(path).with_context(|| format!("failed to read {path:?}"))?;
        bp_contents += "\n";
    }
    Ok(Some(bp_contents))
}

/// Writes the given contents to the given `Android.bp` file, formats it with `bpfmt`, and applies
/// the patch if there is one.
fn write_format_android_bp(
    bp_path: &Path,
    bp_contents: &str,
    patch_path: Option<&Path>,
) -> Result<()> {
    File::create(bp_path)?.write_all(bp_contents.as_bytes())?;

    let bpfmt_output = Command::new("bpfmt").arg("-w").arg(bp_path).output()?;
    if !bpfmt_output.status.success() {
        eprintln!(
            "WARNING: bpfmt -w {:?} failed before patch: {}",
            bp_path,
            String::from_utf8_lossy(&bpfmt_output.stderr)
        );
    }

    if let Some(patch_path) = patch_path {
        let patch_output = Command::new("patch").arg("-s").arg(bp_path).arg(patch_path).output()?;
        if !patch_output.status.success() {
            eprintln!("WARNING: failed to apply patch {:?}", patch_path);
        }
        // Re-run bpfmt after the patch so
        let bpfmt_output = Command::new("bpfmt").arg("-w").arg(bp_path).output()?;
        if !bpfmt_output.status.success() {
            eprintln!(
                "WARNING: bpfmt -w {:?} failed after patch: {}",
                bp_path,
                String::from_utf8_lossy(&bpfmt_output.stderr)
            );
        }
    }

    Ok(())
}

/// Convert a `Crate` into `BpModule`s.
///
/// If messy business logic is necessary, prefer putting it here.
fn crate_to_bp_modules(
    crate_: &Crate,
    cfg: &Config,
    package_cfg: &PackageConfig,
    extra_srcs: &[String],
) -> Result<Vec<BpModule>> {
    let mut modules = Vec::new();
    for crate_type in &crate_.types {
        let host = if package_cfg.device_supported { "" } else { "_host" };
        let rlib = if package_cfg.force_rlib { "_rlib" } else { "" };
        let (module_type, module_name, stem) = match crate_type {
            CrateType::Bin => {
                ("rust_binary".to_string() + host, crate_.name.clone(), crate_.name.clone())
            }
            CrateType::Lib | CrateType::RLib => {
                let stem = "lib".to_string() + &crate_.name;
                ("rust_library".to_string() + rlib + host, stem.clone(), stem)
            }
            CrateType::DyLib => {
                let stem = "lib".to_string() + &crate_.name;
                ("rust_library".to_string() + host + "_dylib", stem.clone() + "_dylib", stem)
            }
            CrateType::CDyLib => {
                let stem = "lib".to_string() + &crate_.name;
                ("rust_ffi".to_string() + host + "_shared", stem.clone() + "_shared", stem)
            }
            CrateType::StaticLib => {
                let stem = "lib".to_string() + &crate_.name;
                ("rust_ffi".to_string() + host + "_static", stem.clone() + "_static", stem)
            }
            CrateType::ProcMacro => {
                let stem = "lib".to_string() + &crate_.name;
                ("rust_proc_macro".to_string(), stem.clone(), stem)
            }
            CrateType::Test | CrateType::TestNoHarness => {
                let suffix = crate_.main_src.to_string_lossy().into_owned();
                let suffix = suffix.replace('/', "_").replace(".rs", "");
                let stem = crate_.package_name.clone() + "_test_" + &suffix;
                if crate_.empty_test {
                    return Ok(Vec::new());
                }
                if crate_type == &CrateType::TestNoHarness {
                    eprintln!(
                        "WARNING: ignoring test \"{}\" with harness=false. not supported yet",
                        stem
                    );
                    return Ok(Vec::new());
                }
                ("rust_test".to_string() + host, stem.clone(), stem)
            }
        };

        let mut m = BpModule::new(module_type.clone());
        let module_name = cfg.module_name_overrides.get(&module_name).unwrap_or(&module_name);
        let module_name = renamed_module(module_name);
        if cfg.module_blocklist.iter().any(|blocked_name| blocked_name == module_name) {
            continue;
        }
        m.props.set("name", module_name.clone());
        if stem != module_name {
            m.props.set("stem", stem);
        }

        if let Some(defaults) = &cfg.global_defaults {
            m.props.set("defaults", vec![defaults.clone()]);
        }

        if package_cfg.host_supported
            && package_cfg.device_supported
            && module_type != "rust_proc_macro"
        {
            m.props.set("host_supported", true);
        }

        if !crate_type.is_test() && package_cfg.host_supported && package_cfg.host_first_multilib {
            m.props.set("compile_multilib", "first");
        }

        m.props.set("crate_name", crate_.name.clone());
        m.props.set("cargo_env_compat", true);

        if let Some(version) = &crate_.version {
            m.props.set("cargo_pkg_version", version.clone());
        }

        if crate_.types.contains(&CrateType::Test) {
            m.props.set("test_suites", vec!["general-tests"]);
            m.props.set("auto_gen_config", true);
            if package_cfg.host_supported {
                m.props.object("test_options").set("unit_test", !package_cfg.no_presubmit);
            }
        }

        let mut srcs = vec![crate_.main_src.to_string_lossy().to_string()];
        srcs.extend(extra_srcs.iter().cloned());
        m.props.set("srcs", srcs);

        m.props.set("edition", crate_.edition.clone());
        m.props.set_if_nonempty("features", crate_.features.clone());
        m.props.set_if_nonempty(
            "cfgs",
            crate_
                .cfgs
                .clone()
                .into_iter()
                .filter(|crate_cfg| !cfg.cfg_blocklist.contains(crate_cfg))
                .collect(),
        );

        let mut flags = Vec::new();
        if !crate_.cap_lints.is_empty() {
            flags.push(crate_.cap_lints.clone());
        }
        flags.extend(crate_.codegens.clone());
        m.props.set_if_nonempty("flags", flags);

        let mut rust_libs = Vec::new();
        let mut proc_macro_libs = Vec::new();
        for extern_dep in &crate_.externs {
            match extern_dep.extern_type {
                ExternType::Rust => rust_libs.push(extern_dep.lib_name.clone()),
                ExternType::ProcMacro => proc_macro_libs.push(extern_dep.lib_name.clone()),
            }
        }

        // Add "lib" prefix and apply name overrides.
        let process_lib_deps = |libs: Vec<String>| -> Vec<String> {
            let mut result = Vec::new();
            for x in libs {
                let module_name = "lib".to_string() + x.as_str();
                let module_name =
                    cfg.module_name_overrides.get(&module_name).unwrap_or(&module_name);
                let module_name = renamed_module(module_name);
                if package_cfg.dep_blocklist.iter().any(|blocked| blocked == module_name) {
                    continue;
                }
                result.push(module_name.to_string());
            }
            result.sort();
            result
        };
        m.props.set_if_nonempty("rustlibs", process_lib_deps(rust_libs));
        m.props.set_if_nonempty("proc_macros", process_lib_deps(proc_macro_libs));
        m.props.set_if_nonempty("static_libs", process_lib_deps(crate_.static_libs.clone()));
        m.props.set_if_nonempty("shared_libs", process_lib_deps(crate_.shared_libs.clone()));

        if package_cfg.device_supported {
            if !crate_type.is_test() {
                if cfg.product_available {
                    m.props.set("product_available", true);
                }
                if cfg.vendor_available {
                    m.props.set("vendor_available", true);
                }
            }
            if crate_type.is_library() {
                m.props.set_if_nonempty("apex_available", cfg.apex_available.clone());
                if let Some(min_sdk_version) = &cfg.min_sdk_version {
                    m.props.set("min_sdk_version", min_sdk_version.clone());
                }
            }
        }
        if crate_type.is_test() {
            if let Some(data) =
                package_cfg.test_data.get(crate_.main_src.to_string_lossy().as_ref())
            {
                m.props.set("data", data.clone());
            }
        } else if package_cfg.no_std {
            m.props.set("prefer_rlib", true);
            m.props.set("no_stdlibs", true);
            let mut stdlibs = vec!["libcompiler_builtins.rust_sysroot", "libcore.rust_sysroot"];
            if package_cfg.alloc {
                stdlibs.push("liballoc.rust_sysroot");
            }
            m.props.set("stdlibs", stdlibs);
        }

        if let Some(visibility) = cfg.module_visibility.get(module_name) {
            m.props.set("visibility", visibility.clone());
        }

        if let Some(path) = &package_cfg.add_module_block {
            let content = std::fs::read_to_string(path)
                .with_context(|| format!("failed to read {path:?}"))?;
            m.props.raw_block = Some(content);
        }

        modules.push(m);
    }
    Ok(modules)
}

#[cfg(test)]
mod tests {
    use super::*;
    use std::env::{current_dir, set_current_dir};
    use std::fs::{self, read_to_string};
    use std::path::PathBuf;

    const TESTDATA_PATH: &str = "testdata";

    #[test]
    fn generate_bp() {
        for testdata_directory_path in testdata_directories() {
            let cfg: Config = serde_json::from_reader(
                File::open(testdata_directory_path.join("cargo_embargo.json"))
                    .expect("Failed to open cargo_embargo.json"),
            )
            .unwrap();
            let crates: Vec<Crate> = serde_json::from_reader(
                File::open(testdata_directory_path.join("crates.json"))
                    .expect("Failed to open crates.json"),
            )
            .unwrap();
            let expected_output =
                read_to_string(testdata_directory_path.join("expected_Android.bp")).unwrap();

            let module_by_package = group_by_package(crates);
            assert_eq!(module_by_package.len(), 1);
            let crates = module_by_package.into_values().next().unwrap();
            let package_name = &crates[0].package_name;
            let def = PackageConfig::default();
            let package_cfg = cfg.package.get(package_name).unwrap_or(&def);

            let old_current_dir = current_dir().unwrap();
            set_current_dir(&testdata_directory_path).unwrap();

            let output = generate_android_bp(
                "// License section.\n",
                &cfg,
                package_cfg,
                package_name,
                &crates,
                None,
            )
            .unwrap()
            .unwrap();

            assert_eq!(output, expected_output);

            set_current_dir(old_current_dir).unwrap();
        }
    }

    #[test]
    fn crate_to_bp_empty() {
        let c = Crate {
            name: "name".to_string(),
            package_name: "package_name".to_string(),
            edition: "2021".to_string(),
            types: vec![],
            ..Default::default()
        };
        let cfg = Config { ..Default::default() };
        let package_cfg = PackageConfig { ..Default::default() };
        let modules = crate_to_bp_modules(&c, &cfg, &package_cfg, &[]).unwrap();

        assert_eq!(modules, vec![]);
    }

    #[test]
    fn crate_to_bp_minimal() {
        let c = Crate {
            name: "name".to_string(),
            package_name: "package_name".to_string(),
            edition: "2021".to_string(),
            types: vec![CrateType::Lib],
            ..Default::default()
        };
        let cfg = Config { ..Default::default() };
        let package_cfg = PackageConfig { ..Default::default() };
        let modules = crate_to_bp_modules(&c, &cfg, &package_cfg, &[]).unwrap();

        assert_eq!(
            modules,
            vec![BpModule {
                module_type: "rust_library".to_string(),
                props: BpProperties {
                    map: [
                        (
                            "apex_available".to_string(),
                            BpValue::List(vec![
                                BpValue::String("//apex_available:platform".to_string()),
                                BpValue::String("//apex_available:anyapex".to_string()),
                            ])
                        ),
                        ("cargo_env_compat".to_string(), BpValue::Bool(true)),
                        ("crate_name".to_string(), BpValue::String("name".to_string())),
                        ("edition".to_string(), BpValue::String("2021".to_string())),
                        ("host_supported".to_string(), BpValue::Bool(true)),
                        ("name".to_string(), BpValue::String("libname".to_string())),
                        ("product_available".to_string(), BpValue::Bool(true)),
                        ("srcs".to_string(), BpValue::List(vec![BpValue::String("".to_string())])),
                        ("vendor_available".to_string(), BpValue::Bool(true)),
                    ]
                    .into_iter()
                    .collect(),
                    raw_block: None
                }
            }]
        );
    }

    #[test]
    fn crate_to_bp_rename() {
        let c = Crate {
            name: "ash".to_string(),
            package_name: "package_name".to_string(),
            edition: "2021".to_string(),
            types: vec![CrateType::Lib],
            ..Default::default()
        };
        let cfg = Config { ..Default::default() };
        let package_cfg = PackageConfig { ..Default::default() };
        let modules = crate_to_bp_modules(&c, &cfg, &package_cfg, &[]).unwrap();

        assert_eq!(
            modules,
            vec![BpModule {
                module_type: "rust_library".to_string(),
                props: BpProperties {
                    map: [
                        (
                            "apex_available".to_string(),
                            BpValue::List(vec![
                                BpValue::String("//apex_available:platform".to_string()),
                                BpValue::String("//apex_available:anyapex".to_string()),
                            ])
                        ),
                        ("cargo_env_compat".to_string(), BpValue::Bool(true)),
                        ("crate_name".to_string(), BpValue::String("ash".to_string())),
                        ("edition".to_string(), BpValue::String("2021".to_string())),
                        ("host_supported".to_string(), BpValue::Bool(true)),
                        ("name".to_string(), BpValue::String("libash_rust".to_string())),
                        ("product_available".to_string(), BpValue::Bool(true)),
                        ("srcs".to_string(), BpValue::List(vec![BpValue::String("".to_string())])),
                        ("stem".to_string(), BpValue::String("libash".to_string())),
                        ("vendor_available".to_string(), BpValue::Bool(true)),
                    ]
                    .into_iter()
                    .collect(),
                    raw_block: None
                }
            }]
        );
    }

    /// Returns a list of directories containing test data.
    ///
    /// Each directory under `testdata/` contains a single test case.
    pub fn testdata_directories() -> Vec<PathBuf> {
        fs::read_dir(TESTDATA_PATH)
            .expect("Failed to read testdata directory")
            .filter_map(|entry| {
                let entry = entry.expect("Error reading testdata directory entry");
                if entry
                    .file_type()
                    .expect("Error getting metadata for testdata subdirectory")
                    .is_dir()
                {
                    Some(entry.path())
                } else {
                    None
                }
            })
            .collect()
    }
}